In archery, and particularly bow hunting, arrow speed is dependent upon several factors, one being the amount of energy or force the bow is able to develop and deliver to the arrow. Generally speaking the more total energy put into the bow, the faster the arrow will be propelled. Increased arrow speed is desirable, especially when hunting with or shooting heavy arrows and over greater distances. However, the operation of a bow with greater energy or force is difficult because of the effort required to draw the bowstring, and for this reason many people are not capable of producing sufficient force to provide a traditional bow (e.g., compound bows) with the necessary energy to effectively propel the arrow. Even persons who have sufficient strength to draw a bow find it difficult to shoot accurately since aiming the bow and holding the drawn bowstring must be accomplished simultaneously, absent any extraneous motion, and the drawn position must sometimes be maintained for many seconds and even minutes before the target is clear for a shot.
In response to the shortcomings of the long bow and recurve bow, the compound bow was developed. The compound bow offers several mechanical advantages over traditional straight and recurve bows. By and large, compound bows provide more thrust than non-compound bows, and often have a “let-off” whereby the bow may be maintained in a drawn position with less force than was necessary to initially draw the bow. Also, a compound bow is generally more compact in terms of size for a given energy capacity.
In order for a compound bow to be effective, by current standards, it must be capable of producing a specific level of performance in terms of arrow velocity and accuracy. Acceptable performance with respect to arrow velocity is defined within industry standards established by the Archery Trade Association (ATA) where about a 60 lb. peak draw force, being drawn back a distance of 30 in. will propel a 540 grain arrow at a velocity within a range of 200 to 250 feet per second (140-170 MPH). Accuracy, on the other hand, is subjective because the level of precision shooting obtainable with any given bow is not controlled by the bow alone, but rather the product of the bow/arrow/archer combination. However, one characteristics of a bow design that tends to be more influential towards accuracy is arrow velocity. The trajectory, or arc, of an arrow is increasingly diminished (i.e., closer to a straight-line) as arrow velocity increases, therefore providing a more predictable and straight-line placement of the arrow relative to the target.
Accordingly, a compound bow is designed to provide a mechanical advantage in order to reduce the force that an archer must apply to the bow while increasing the overall energy stored by the bow. Most compound bow designs use cams or elliptical wheels on the ends of the riser to optimize the leverage exerted by the archer and to reduce or “let-off” the holding force of the bow as a full draw is approached. Let-off, as noted above, is when the force required to hold the bowstring at full draw is substantially less than the force required to draw or hold the bowstring in an intermediate position between the undrawn and fully drawn positions. Upon release of a bowstring, which has been loaded with an arrow, the force propelling the arrow at a given position while nocked on the bowstring is proportional to the force required to hold the bowstring stationary in that position. In accordance with an aspect of the disclosed embodiments, using means such as levers to provide mechanical advantage, and a drawing mechanism, less force is required to hold a bow at full draw. As a result the muscles take longer to fatigue, thus giving the archer or hunter sufficient time to relax and aim, similar to the advantages of a compound bow or even a cross bow. In accordance with other aspects of the devices disclosed herein, the adjustability of such devices permit the use of the device across a wide range of users (e.g., sizes, arm length, strength), and permit a smaller size than conventional archery equipment.
In recent years, a number of improvements have been made to compound bows; most notably the use of the bowstring and associated springs to store potential energy having a non-linear power curve. This has proven to significantly enhance the overall control of the force applied to the arrow when the bowstring is released because the high potential energy is not instantaneously captured by the arrow in the form of kinetic energy at the moment the bowstring is released, thereby avoiding accuracy degradation resulting from the imparted shock.
In this regard, compound archery bows have been devised by generally utilizing a rigging of the bowstring with respect to one or more cams or pulleys that are rotatably mounted to a riser having a compression spring therebetween. In this configuration the bowstring is pulled by the archer to compress or expand the springs having an arrow nocked to the bowstring. While the flexible bowstring remains an effective means to transmit the propelling force from the spring to the arrow, it is less than effective as a “crank” to wind up springs due to its small cross-section and flexibility. An improvement to conventional devices includes applying a rotational force to a “spring,” as found in the disclosed embodiments. Although various means for energizing the spring may be disclosed, one means includes a rigid lever having an ergonomic handle, such that the lever may be employed to energize the spring. In the case of a bow, the disclosed embodiment serves to relieve the archer of discomfort resulting from pulling on a string with the index and middle fingers (or via a wrist-attached release mechanism) by providing a discrete rigid lever action member having a user friendly linkage to place the bow in a fully drawn position, without the archer having any direct interaction with the loaded bowstring and arrow. Such a device is not only believed to provide an adjustable (customizable) archery device, but to further improve safety by reducing the likelihood or unintentional release of arrows when a user exerts significant draw force.
Accordingly, it is the object of the disclosed embodiments to provide a bow with a linked lever for the angular rotation of at least one spring motor to provide a propelling force to the bowstring, which thereby transfers the force to the arrow shaft.
It is also an object of the disclosed device or system to provide a spring driven, high-energy “bow” wherein the required drawing and holding force may be achieved independently of the bowstring, the bow also having a trigger or similar mechanism for the release and transfer of the spring-stored energy to the bowstring.
In accordance with yet another aspect of the disclosed device, the spring driven bow includes a bowstring that is directly linked or connected to elements of at least one spring motor.
Another object of the inventive device is to provide an archery bow in which at least one wound torsion spring is used as the energy storing medium.
It is a further object to provide an improved bow that is compact, efficient, powerful, ergonomic, lightweight and is also distinct in appearance, operation and portability.
Other and further objects, features and advantages will be evident from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein the examples of the presently preferred embodiments are given for the purposes of disclosure.
In accordance with one aspect of the disclosed embodiments there is provided a projectile launching device (bow), comprising; a rigid riser; a hand grip operatively associated with said riser; at least one spring assembly operatively connected to said rigid riser, said spring assembly including a rotating member operatively associated therewith; a string operatively associated with said spring assembly such that each end of the bowstring is attached to the rotating member; a projectile releasably attached to said bowstring; and means to energize said spring assembly, where upon release of energy stored in said spring assembly said rotating member rotates and said bowstring to launches the projectile.
In accordance with another aspect of the disclosed embodiments, there is provided an archery bow, comprising: a rigid riser; a hand grip operatively associated with said riser; at least one spring assembly operatively connected to said rigid riser, said spring assembly including a spring and a rotating member operatively associated therewith; a string operatively associated with said spring assembly such that each end of the bowstring is attached to the rotating member; an arrow releasably attached to said bowstring; and a pair of engaged spring cranks releasably connected to said spring assembly to energize said assembly and rotate said rotating member in a first direction, where upon release of energy stored in said spring said rotating member rotates in a second direction, opposite the first direction, applying increased tension to the bowstring and launching the arrow.
In accordance with another aspect of the disclosed embodiments, there is provided a method for drawing and releasing a bow to propel an arrow, comprising: applying a linear drawing force to move a pair of engaged spring cranks, the cranks being releasably connected to a spring assembly, to energize said spring by rotating a member attached to said spring in a first radial direction; concurrently drawing a bowstring, with an arrow nocked thereto, said bowstring having each end thereof attached to the member; decoupling the spring assembly from the spring cranks; and releasing energy stored in said spring wherein said member rotates in a second direction, opposite the first direction, and said bowstring propels the arrow.
Other and further objects, features and advantages will be evident from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein the examples of the presently preferred embodiments are given for the purposes of disclosure.
The various embodiments described and depicted herein are not intended to limit the scope to those embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the appended claims.